Chelated plant micronutrients

ABSTRACT

The present invention relates to chelated plant micronutrients of the sodium, potassium, sodium/ammonium or potassium/ammonium salts of N-(1,2-dicarboxyethyl)-D,L-aspartic acid and their mixtures with metal ions selected from the group of the inorganic or organic zinc, manganese, iron(II), iron(III) or copper(II) compounds, and to a process for the preparation of these chelated micronutrient fertilizers.

This application is a continuation of U.S. patent application Ser. No.10/684,925 filed Oct. 14, 2003, incorporated herein by reference.

BACKGROUND

The present invention relates to chelated plant micronutrientscomprising the reaction product of the sodium, potassium,sodium/ammonium or potassium/ammonium salts ofN-(1,2-dicarboxyethyl)-D,L-aspartic acid and their mixtures with metalions selected from the group of the inorganic or organic zinc,manganese, iron(II), iron(III) or copper(II) compounds, and to a processfor the preparation of these chelated micronutrient fertilizers.

Micronutrients such as iron, copper, zinc and manganese are applied inorder to ensure proper plant growth. Micronutrients in chelated form aretaken up better by the plants, and deficiency, which leads to reducedyields, is compensated for.

The use of metal ions in chelated form which are prepared with suitablecomplexing agents with high stability constants is already known fromthe prior art. Chelated metal ions ensure a rapid uptake andtranslocation within the plant under different growth conditions, suchas soil pH, interaction between soil components, climatic conditions,bicarbonate content, redox potential and other parameters.

Chelated iron(II), iron(III), manganese, copper and zinc ions are usedin the form of individual trace elements or in the form of mixtures andas additives for NPK complete or compound fertilizer(NPK=nitrogen-phosphorus-potash).

For example, the patent DE-A 3 517 102 discloses a liquid fertilizercomprising chelated iron (III), manganese, copper, zinc or cobalt in theform of nitrates having a pH of 4 to 8 and a concentration of 40.3% upto 62.7% of the dry matter. In the abovementioned prior art, thechelating agents nitrilotriacetic acid (NTA), ethylenediaminotetraaceticacid (EDTA), diethylenetriaminopentaacetic acid (DTPA),N-hydroxyethylethylene-diaminotriacetic acid (HEEDTA),ethylenediaminedi(o-hydroxyphenylacetic acid) (EDDHA) are usedseparately or in combination with their sodium, potassium and ammoniumsalts in a molar ratio of metal to chelating agent of at least 0.1:1.0to 5:1, preferably 0.8:1 to 2.5:1.0.

Most of the synthetic chelating agents mentioned in the prior art arenot biodegradable and, accordingly, accumulate in soils and watercourses.

DE-A 1 0219 037 describes a process for the preparation ofammonium/metal salts of iminodisuccinic acid and their possible use asmicronutrient fertilizers. However, it lacks any suggestion that thedivalent, trivalent or tetravalent alkali metal or alkali metal/ammoniummixed salts of N-(1,2-dicarboxyethyl)-D,L-aspartic acid or theirmixtures meet the demands of a biodegradable micronutrient fertilizerparticularly well.

It was therefore an object of the invention to provide the plants withplant micronutrients in chelated form, to bind the micronutrients inchelated form and to provide the plants with sufficient amounts of thelatter, combined with as high as possible a biodegradability of thechelating agents.

SUMMARY OF THE INVENTION

The invention relates to a composition comprising a chelated plantmicronutrient including the reaction product of (i) a salt componentselected from the group consisting of sodium salts ofN-(1,2-dicarboxyethyl)-D,L-aspartic acid, potassium salts ofN-(1,2-dicarboxyethyl)-D,L-aspartic acid, sodium/ammonium salts ofN-(1,2-dicarboxyethyl)-D,L-aspartic acid, potassium/ammonium salts ofN-(1,2-dicarboxyethyl)-D,L-aspartic acid, and mixtures thereof with (ii)a metal ion component selected from the group of the inorganic zinc,organic zinc, manganese, iron(II), iron(III) compounds, copper(II)compounds, and combinations thereof.

In one embodiment, the invention relates to a process for making aliquid micronutrient comprising (a) chealating (1) a complexing agent Ahaving an imino group and polycarboxyl groups with (2) an inorganiccompound B of a chloride, nitrate, acetate, sulphate, carbonate,hydroxide or oxids of the polyvalent metal ions of iron, manganese,copper or zinc, and (b) adding an inorganic acid or an organic acid, andthereby forming the liquid micronutrient.

In another embodiment, the invention relates to a process for preparinga solid chelating plant micronutrient comprising drying a liquidmicronutrient in a spray drier, and thereby forming the solid chealatingplant nutrient, such that the liquid micronutrient is prepared by (a)chealating (1) a complexing agent A having an imino group andpolycarboxyl groups with (2) an inorganic compound B of a chloride,nitrate, acetate, sulfate, carbonate, hydroxide or oxids of thepolyvalent metal ions of iron, manganese, copper or zinc, and (b) addingan inorganic acid or an organic acid, and thereby forming the solidchealating plant micronutrient.

In another embodiment, the invention relates to a method for fertilizinga plant comprising treating a plant with a composition comprising achelated plant micronutrient including the reaction product of (i) asalt component selected from the group consisting of sodium salts ofN-(1,2-dicarboxyethyl)-D,L-aspartic acid, potassium salts ofN-(1,2-dicarboxyethyl)-D,L-aspartic acid, sodium/ammonium salts ofN-(1,2-dicarboxyethyl)-D,L-aspartic acid, potassium/ammonium salts ofN-(1,2-dicarboxyethyl)-D,L-aspartic acid, and mixtures thereof with (ii)a metal ion component selected from the group of the inorganic zinc,organic zinc, manganese, iron(II), iron(III) compounds, copper(II)compounds, and combinations thereof, and thereby treating the plant.

These and other features, aspects, and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims.

DESCRIPTION

The object of the invention is achieved by providing the plants to betreated with chelated micronutrients comprising the divalent, trivalentor tetravalent alkali metal or alkali metal ammonium mixed salts ofN-(1,2-dicarboxyethyl)-D,L-aspartic acid or their mixtures as compound Aand polyvalent metal ions selected from the group of Fe(III), Fe (II),Mn, Cu or Zn as compound B, as well as conventionally used additives.

The chelated plant nutrients are to be at least about 70.0%biodegradable over a period of 28 days as specified in OECD GuidelineNo. 301 E. They are therefore outstandingly suitable for fertilizingplants, in particular useful plants.

The invention preferably relates to compounds of the formula A

where

-   -   X represents potassium, sodium, ammonium or hydrogen and the        degree of substitution for potassium and/or sodium is in the        range from 2 to 4, preferably 3.5 to 4, and the degree of        substitution for hydrogen and/or ammonium in the range from 0 to        2, preferably 0 to 0.5.        This results for example in the following substitution patterns:        3 X are sodium and 1 X is hydrogen or 4 X are sodium or 3 X are        sodium and 1 X is ammonium or 3 X are potassium and 1 X is        hydrogen or 4 X are potassium or 3 X are potassium and 1 X is        ammonium or 2 X are potassium and 1 X is ammonium and 1 X is        hydrogen.

Preferred compounds B are in accordance with the invention carbonates,chlorides, sulphates, oxides, hydroxides, acetates and nitrates of themetals iron (III), iron (II), manganese, copper and zinc.

Preferred in accordance with the invention is a molar ratio between thechelating agent A and the metal ion B in the range from about 1.3-0.8 toabout 1.0-0.9. In one embodiment, the complexing agent and the metal ionare at a molar ratio ranging from about 1.0:0.8 to about 1.0:0.98.

The chelated micronutrients according to the invention are prepared inliquid or else in solid form and optionally contain conventionally usedadditives.

The liquid products according to the invention contain from about 1.0 toabout 6.0% by weight of the micronutrient, the preferred molar ratio tothe chelating agent being from about 0.95 to about 1.0.

The solid products according to the invention contain from about 5.0 toabout 14.0% by weight of the micronutrient, the preferred molar ratio tothe chelating agent being from about 0.95 to about 1.0.

Moreover, the chelated micronutrients according to the invention maycontain other micronutrients which are used in agriculture, horticultureor hydroponics, such as calcium, magnesium, boron, molybdenum or cobalt.

It has been found that the chelated micronutrients according to theinvention can be applied as individual chelates or mixtures thereof withother known complex-forming compounds from the series of theaminopolycarboxyl compounds, polyaminocarboxyl compounds, poly- andbicarboxyl compounds, hydroxypolycarboxyl compounds,hydroxypolyaminocarboxyl compounds and, if appropriate, as a constituentof NPK complete and compound fertilizers, which widens their field ofapplication and increases their efficacy.

Preferred complete fertilizers are nitrogen fertilizers such as forexample UAN-solution 30,0%, phosphorus fertilizers such as for exampleMAP or DAP or potash fertilizers such as for example MOP, SOP, KNO₃ orcombinations thereof.

It is preferred in accordance with the invention for the chelated plantmicronutrient additionally to contain wetting agents or adhesives.Wetting agents or adhesives which are preferred in accordance with theinvention are Cycocel®, lignosulfonates or gluconates.

The present invention furthermore relates to a process for thepreparation of the finished products in solid or liquid form.

Chelating is effected by reaction of the complexing agent A having animino group and polyhydroxyl groups and an inorganic compound B of achloride, nitrate, acetate, sulfate of the polyvalent metal ions, ofiron, manganese, copper or zinc, or said complexing agent A is reactedwith an inorganic compound C of a hydroxide, carbonate or oxide of thesame polyvalent metal ions with addition of inorganic or organic acids.Preferred acids for the purposes of the present invention arehydrochloric acid, sulfuric acid, nitric acid or acetic acid.

In order to convert the resulting products into solid form, the liquidmicronutrient fertilizers are dried in a spray-drier. To this end, theliquid products are advantageously first filtered and then sprayed intoa spray tower at a pressure ranging from about 15 to about 60 bar,preferably from about 35 to about 45 bar, using suitable nozzles. Theinlet temperature of the spray tower is from about 100 to about 300° C.,preferably from about 120 to about 250° C., and the outlet temperatureis from about 50 to about 150° C., preferably from about 70 to about120° C. This gives almost dust-free microgranules with a particle sizeof from about 50 to about 400 μm, preferably from about 80 to about 300μm. It has proved advantageous to cool the microgranules as they areobtained to approx. about 30° C. and to condition them with anantiadhesive. Products which can be used for this purpose are, forexample, those of the Hostapur® series of products.

The micronutrient can be applied in agricultural applications,horticulture applications. Possible ways of applying the liquid productor solid product according to the invention include foliar sprays, soilapplication, hydroponics and fertigation.

The invention is further described in the following illustrativeexamples in which all parts and percentages are by weight unlessotherwise indicated.

EXAMPLES Example 1

23 ml of a stirred 34% tetrasodium N-(1,2-dicarboxyethyl)-D,L-aspartatesolution were treated at 40° C. with 20 ml of an 18.0% zinc chloridesolution.

Following reaction for one hour after addition of 0.3% lignosulfonate asadhesive, a storage-stable transparent solution was obtained. The Zncontent was 3.74% by weight.

Example 2

19.6 ml of a stirred 34% tetrasodiumN-(1,2-dicarboxyethyl)-D,L-aspartate solution were treated dropwise at60° C. with 20 ml of a 20% manganese(II) nitrate solution.

After 2 hours of reaction at 60° C., 0.5% Cycocel® was added as wettingagent, whereby a storage-stable orange transparent solution wasobtained.

The Mn content was 2.9% by weight (w/w).

Example 3

12.9 ml of a stirred 47.0% ammonium dipotassiumN-(1,2-dicarboxyethyl)-D,L-aspartate solution were treated at 40° C.with 20 ml of a 27.0% copper(II) nitrate solution.

After 2 hours of reaction at 40° C., 0.5% Cycocel® was added as wettingagent, whereby a storage-stable blue transparent solution was obtained.

The Cu content was 3.8% by weight.

Example 4

20 ml of a stirred 12.0% iron(III) nitrate solution were treated at 40°C. with 11.5 ml of a 34% tetrasodiumN-(1,2-dicarboxyethyl)-D,L-aspartate solution.

After reaction for 2 hours with exclusion of light at 40° C., 0.5%Cycocel® and 0.5% lignosulfonate were added as wetting agent andadhesive, respectively, whereby a storage-stable dark green transparentsolution was obtained. The Fe(II) content was 2.22% by weight.

Example 5

20 ml of a stirred 12.0% iron(III) nitrate solution were treated at 60°C. with 11.5 ml of a 34% tetrasodiumN-(1,2-dicarboxyethyl)-D,L-aspartate solution.

After reaction for 1 hour, 0.5% of oxidant as well as 0.5% of Cycocel®and 0.5% of gluconate as wetting agent and adhesive, respectively, wereadded, and stirring was continued for 1 hour.

The final solution was a storage-stable transparent dark red liquid. TheFe(III) content was 2.2% by weight.

Example 6

393.5 ml of a stirred 34.0% tetrasodiumN-(1,2-dicarboxyethyl)-D,L-aspartate solution were treated at 60° C.with 45 ml of a 20.0% zinc nitrate solution, 33.7 ml of a 27.0%copper(II) nitrate solution, 310.5 ml of a 12.0% iron(III)nitratesolution, 133.8 ml of a 20.0% manganese nitrate solution, 13.7 g ofboric acid and 60.8 g of magnesium nitrate.

After reaction for 2 hours at 60° C., a storage-stable transparent darkgreen solution was obtained. The solution contained: Zn 0.3% Cu 0.3% Fe1.1% Mn 0.8% B 0.2% MgO 0.8%

All percentages are by weight.

Example 7

23 ml of a 34,0% tetrasodium n-(1,2-dicarboxy-ethyl) - D,L aspartatesolution and 2,39 g zinc oxide (79,4% ZnO) was treated at 40° C. with7,2 g of nitric acid 55,0%.

After reaction for 2 hours the solution was filtrated whereby astorage-stable transparent liquid was obtained. The Zn content was 4,65%by weight.

Although the invention has been described in detail in the foregoing forthe purpose of illustration, it is to be understood that such detail issolely for that purpose and that variations can be made therein by thoseskilled in the art without departing from the spirit and scope of theinvention except as it may be limited by the claims.

1. Chelated plant micronutrients including the reaction product ofsodium and/or potassium salts of N-(1,2-dicarboxyethyl)-D,L-asparticacid, and/or combinations thereof, as compounds of formula (A)

wherein X represents potassium, sodium or hydrogen and the degree ofsubstitution of potassium and/or sodium is in the range of from 3.5 to4, and the degree of substitution for hydrogen is in the range of from 0to 0.5, and a compound (B) comprising an inorganic and/or organic zinc,manganese, iron(II), Iron(III) or copper(II) compound.
 2. Themicronutrients according to claim 1, wherein the sodium salt comprisesthe tetra sodium salt of N-(1,2-dicarboxyethyl) D,L-aspartic acid. 3.The micronutrient according to claim 1, wherein the molar ratio betweenCompound (A) and Compound (B) is in the range of from 1.3:0.8 to1.0:0.9.
 4. The micronutrient according to claim 1, wherein the reactionproduct is present in liquid form and comprises 1.0 to 6.0% by weight ofmetal ions.
 5. The micronutrient according to claim 1, wherein thereaction product is present in solid form and contains 5.0 to 14.0% byweight of metal ions.
 6. The micronutrient according to claim 1, furthercomprising additional micronutrients.
 7. The micronutrient according toclaim 6 wherein the additional micronutrients include magnesium, boron,molybdenum, calcium and/or cobalt.
 8. The micronutrient according toclaim 1, further comprising at least one additional complexing agentfrom compounds including animopolycarboxyl compounds, polyaminocarboxylcompounds, hydroxypolyaminocarboxyl compounds and/or hydroxypolycarboxylcompounds.
 9. The micronutrient according to claim 1, further comprisingNPK fertilizer.
 10. The micronutrient according to claim 9, whereinfertilizer includes nitrogen, phosphorus, potash, and/or mixturesthereof.
 11. The micronutrient according to claim 9, further comprisingconventional wetting agents and/or adhesives.
 12. A method for providingplants with micronutrients in chelated form comprising: a. applying to aplant the reaction product according to claim
 1. 13. The method of claim12 wherein the application comprises foliar spray, soil application,hydrophonics and fertigation.